Wait, do british novels really get "translated" to american english? This seems to have way too little gain for that much effort.
Sometimes, yes. As Paris alluded to, the first few Harry Potter novels had their language tweaked for American audiences, but later books' US editions were largely unchanged, because by then it would've been seen as blasphemy to change Rowling's words. (The difference in those US editions was in the cover art, physical formatting, etc.)